Two-piece cans are widely used in the beverage industry to package soft drinks, alcoholic drinks, and the like. These two-piece beverage cans typically include a thin-walled tubular body portion having an integral closed end opposite an open end. The open end is subsequently sealed by a can end (also known as a lid) once the can body has been filled with a liquid beverage.
Can bodies are produced from a metal sheet product, typically aluminum or steel. The aluminum or steel sheet arrives at the can manufacturing plant in very large coils. The sheet is fed continuously from an uncoiler or payoff reel into a cupping press which cuts out thousands of disks per minute and forms them into shallow cups. This is called the blank and draw process.
The shallow cups are transported to a bodymaker where the can body begins to take its final shape. In the bodymaker, the shallow cup goes through a process called draw and iron or “DI”. During DI, the shallow cup is placed in front of a moving ram which forces it through a series of precision rings, each a little smaller than the previous. This reduces the thickness of the metal (wall ironing) and, as a result, the can gets taller. At the end of the stroke the bottom is formed, and the can body is removed from the ram.
A trimmer shears material excess about the open end of the can body. This trimming process insures that the can body is the correct height, and that the rim about the open end is uniform and free of earring (misshapen metal). Again, the surplus material from this process is recycled.
The trimmed can bodies then pass through highly efficient washers to remove lubricants used during the forming process and to prepare the can body outer surface for coating and printing. Cans are then dried in a drier or oven.
Depending on customer and design requirements, the outer surface of the can bodies may be externally coated with a white or clear base coat at a base coater station.
The next step is a highly sophisticated decorator, which applies a design to the outer surface of the can body using up to six colors. All six colors are printed onto the can body in the same operation. A clear-coat over-varnish is sometimes added to the printed can bodies to give a glossy finish.
Next, the inner surface of each can body is sprayed with a coating. This special layer is added to protect the product in the can from interaction with the metal of the can body.
The decorated can bodies are then passed through a necker/flanger which reduces the diameter of the open end of the can body. This gives the can bodies the characteristic neck shape. Here, the diameter of the top of the can is reduced or “necked-in”. The top of the can body is flanged outwards to enable the can end to be seamed to the can body after the can bodies are filled with a liquid beverage.
Can body decorating is an important step in the manufacturing process. Beverage companies often seek to differentiate their brands based on the look of the containers that hold their products. Any deviation from the design of the art on the can body is undesirable from a beverage company's point of view. Therefore, it is very important to manufacturers that their can body decorating machines operate in a manner that does not introduce variability in the decorations exhibited from one can body to the next in a plurality of consecutively decorated can bodies.
Additionally, the economics associated with can body production make it highly desirable for the can body manufacturing process to take as little time as possible. In other words, manufacturers seek to increase production speeds whenever possible. However, an increased speed in one process can lead to an undesirable result in a subsequent manufacturing step.
One difficulty encountered in can body decorating occurs during the transfer of the can bodies to and from the decorating apparatus. Additionally, the can bodies themselves may exhibited voids, i.e. portions having no ink in locations that should exhibit inked decoration.
The problems addressed by the present invention can be stated as follows: In a manufacturing process to produce can bodies for a two-piece beverage container, how might can body performance within a can body decorating apparatus be improved and how might visual results achieved by the can body decorating apparatus be improved.
The present invention is provided to solve the problems discussed above and other problems, and to provide advantages and aspects not provided by prior end closures of this type. A full discussion of the features and advantages of the present invention is deferred to the following detailed description, which proceeds with reference to the accompanying drawings.